Propeller



Sept. 30, 1941. A. 5. RINDFLEISCH 2,257,126

PROPELLER Filed Jan. 27, 1936 5 Sheets-Sheet l INVENTOR.

ARTHUR 6. RINDFL E/scH.

ATTORNEY.

Sept. 30, 1941. A. e. RINDFLEISCH PROPELLER Filed Jan. 27, 1936 5 Sheets-Sheet 2 5 2.. an S Q A m w r M o: 8. n: on a I L6 5A 6 m m 44 W Om M .P x o an E r m mv 3 Ja v 2 da l I am a k an 3 2. w a n 5; Q2 3 7 3 an L2. L 0 n E INVENTOR. ARTHUR G. RINDFLEISCH.

ATTORNEY.

Sept. 30, 1941.

A. a. RINDFLEISCH PROPELLER F iled Jan. 27, 1936 5 Sheets-Sheet 3 INVENTOR. ARTHUR 6. R/NOFLE/SCH.

ATTO'RNEY.

P 30, 1941. A. a. RINDFLEISCH 2,257,126

PROPELLER Filed Jan. 27, 19:56 5 Sheets-Sheet 5 I19- 5.. I .19.. lU

CYUNDER FULL FEATHERING COLLECTOR RING.

CYLINDER INVENTOR. ARTHUR G. RINDFLEISCH- ATTORNE Y.

COHTROLL ABLE PITCH Patented Sept. 30, 1941 PROPELLER Arthur G. Rindfleisch, Cincinnati, Ohio, assignor to Bocjl Corporation, trustee, Pittsburgh, Pa., a

corporation of Delaware Application January 27, 1936, Serial No. 60,949

32 Claims.

My invention relates to an aircraft propeller and more particularly to one with an automatic selective pitch, that is; one which automatically adjusts itself to the proper pitch relative to the R. P. M. of the propeller and the horsepower of the motor, to maintain the propeller at a constant rotativ speed.

In the operation of aircraft, it is well recognized that a variable or controllable pitch propeller, which pitch can be controlled while the aircraft is in a state of flight, will give a superior performance over a constant pitch propeller. Broadly speaking the reason for this, is that, if the pitch of the propeller is set at such an angle which will give the most economical engin performance at cruising speed (as in the case of a constant pitch propeller), then the pitch of this same propeller will not give the most satisfactory results when the aircraft is taking off, or when in a climb, or other maneuvers. This is due to the fact that the engine will not be capable of turning the the dead propeller, resulting in a higher lift. This is especially significant in the case of multi-motored ships in the event that a motor is cut out due to mechanical or other reasons.

The primary object of my invention is to provide a propeller construction which is variable and automatically controllable by a, governing mechanism which is regulated by the rotatlve speed of the propeller during the various maneuvers of the aircraft, or by an increase or decrease in the engin power, or both.

A further object is to provide an isolated independent fluid pressure and control system for operating automatically the pitch changes of the propeller.

A further object is to provide automatic means for full feathering the propeller.

A further object is to provide emergency means controlled by the pilot for full feathering the propropeller at its maximum R. P. M. or produce peller.

A further object is to provide manual control means for changing the pitch of the propeller.

A further object is to provide novel means for attaching and supporting the propeller blades on the hub.

My invention will be further readily understood from the following description and claims,

and from the drawings, in which latter:

including the take-off or when in a climb.

Therefore the angle of attack of the aircraft can be increased at the time of take-off or when in a climb and as a result of this permit the air craft to take-off in a shorter run or with an in-' creased load.

In order to meet these conditions, it is obvious that the pitch of the propeller should be variable and controllable relative to the rated horsepower of the engine and the R. P. M. of the propeller, and it is also desirable that the pitch be automatically controlled by the R. P. M. of the propeller as well as being capable of control by the pilot.

Therefore in my improved construction I have incorporated means for automatically increasing or decreasing the pitch of the propeller controlled.

by the R. P. M. of the propeller, as well as means for manual control and means for automatically and manually changing the pitch of the propeller to a full feathering position, in which position the propeller will offer the least resistance to th air and eliminate the windmill effect, due to the blades entering the airstream edgewise instead of broadside, when the engine is dead or the throttle is closed, giving a smoother flow of air Fig. 1 is a. plan view of the propeller head, with one of the blade mountings in section.

Fig. 2 is a longitudinal section of the same, taken in the plane of the line 22 of Fig. 1.

Fig. 3 is a side view of the propeller head.-

Fig. 4 is a cross-section of th same, taken in the plane of the line 4-4 of Fig. 3.

Fig. 5 is a cross-section of the same, taken in the plane of the line 55 of Fig. 2.

Fig. 6 is a cross-section of the same, taken in the plane of the line 66 of Fig. 2.

Fig. 7 is a detail section of the governor mechanism and manual control therefor, taken in the plane of the line 'l l of Fig. 4.

Fig. 8 is a detail, taken in the plane of the line 88 of Fig. 7.

Fig. 9 is a detail section, taken in the plane of the line 9-9 of Fig. 2.

Fig. 10 is a detail section, taken on the line illl 0 of Fig. 2, and;

t Fig. 11 is a diagrammatic view of the fluid sys- In the particular embodiment of the invention illustrated, the propeller blades which are adjustable over a range between a low pitch and a high pitch position and also to a full feathered over that section of the wing within the zone of position, are adjusted inthe automatic operation thereof by two expansible chamber fluid pressure motors. one motor adjusting the blades in the range between low and high pitch positions;

the second moving the blades to the full feathered position. Fluid pressure is supplied from a iluld circulating system with pumping means therein.

In the drawings I have shown myimproved propeller construction mounted on a' standard aircraft motor, in which the crankcase is indicated at 2|, having the usual bearing 22 for the propeller drive shaft 23. A hub'structure 24 is keyed to the shaft 26 as at 26 and clamped thereon as by a threaded connection 26 with a plate 21. The plate is also suitably bolted to the hub as by bolts 26.

Extending outwardly from the hub 24 are stud shafts 29, on which the propeller blades 66 are rotatably mounted, having ball bearings 3| individually held on the shaft by nuts 32. The inner or root end of the blade is internally threaded to receive a nut 33 which clamps the outer raceways of the ball bearings 3| in the propeller blade. Thus the ball bearings absorb the thrust, centrifugal and torque loads of the propellers when in a state of rotation, and such loads are equally carried by the raceways of each of the bearings. In the present instance I have shown four such bearings and each hearing will carry one-fourth of the load. I

While I have shown two propeller blades in the drawings, it is apparentthatthe same structure can be employed in a propeller construction having more than two blades.

Secured to the forward face of the plate 21 is a housing 34 forming a reservoir for the fluid used to operate the mechanism for changing the pitch of the propeller and also forms a guide for the cylinder and piston hereinafter described. Th s housing 34 is suitably bolted to the plate as by bolts 36.

Secured to the crankcase is a 'gear 36. Planetary gears 31 rotate with the hub structure around the gear 36 and impart rotation to the gear pumps 36 through the shafts 39, which are joumaled in bearings 46 in a gear housing 4| attached to the hub structure and bearings 42 in the plate 21.

The housing 34 forms a central reservoir 43, with gear pump chambers 44 having connecting ports 46 with the reservoir. The housing is also provided with cavities 46 and 41 for the governor mechanism having connection with and forming part of the fluid reservoir. The housing extends outwardly forming a guide or fixed piston 46 for the cylinder 49 constituting the movable element of the expansible chamber motor which varies the pitch of the blades, and a cylinder 66 for the piston 6|, which is the movable part ofthe expansible chamber motor through which full feathering of the blades is accomplished.

Ports 62 and 63 in the plate 21 connect with a transverse passage 64. A relief port 66 connects with the passage 64 and has a'check valve 66. therein, The setting of this check valve governs the pressure in the passages. A passage 61 having connection with the passage 64, has the governor actuated valve 66 therein, for opening or closing said passage to a cross passage 69, and

' connecting with the tube 66 which forms a passage to the automatic pitch changing cylinder 49. The passage 66 also connects with a passage 62 having a governor actuated valve 63 therein, for opening and closing said passage 62 for connection with a return port 64. which connects with the reservoir 43. A passage 66 having connection with the passage 64, has the full feathering governor controlled valve 66 therein, for opening or closing said passage to a cross passage 61. A passage 66 connects the passage 61 with a passage 66 leading to the full feathering cylinder 66. The fluid in returning to the reservoir passes from the cylinder 66 through the passage 69, passage 66, passage 61, through passage 1| which has a governor actuated valve 12 therein, for opening and closing said passage to the return port 16 leading to the reservoir. A breather port 14 has a passage 16 through the plate to which a tube 16 connects and encircles the plate.

The automatic pitch cylinder 49 encompassesthe reservoir housing and has a bearing on the outer periphery 16 of the full feathering cylinder 66, which is concentric with the reservoir and integral therewith. The cylinder 49 is provided with a collar 6| arranged to limit the endwise movement of the nose housing 62, which is provided with engaging peripheral stops 63 and 64. A collar 66 is threaded to theend of the cylinder 66 and pinned thereto. This collar has splines 66 engaging splineways 61 in the piston 6|. The nose housing 62 is threaded to the piston 6| with reverse threads whereby the rotative force will change the pitch of the propeller blades to compensate for varying conditions while in flight as well as in taking oil and landing. I accomplish this change in pitch automatically by means of a governor mechanism controlled by the R. P. M.

of the propeller. The governor mechanism is received in the cavity 46 and comprises a shaft I66 supported in bearings I 6| and I62 in the plate and housing respectively. A collar I63 is fixed on the shaft and has extending arms I64 and I66 engaging the stems of valves 68 and 63. The governor I66 is fixed to the shaft and comprises a pair of spaced apart arms having a weight or ball I61 secured to the extending ends. A

pair of arms I 66 are pivoted on the governor shaft and have extending pins I69 at their free ends to which springs II6 are secured, with the other ends of the springs secured to pins on the governor arms I66. A cross-bar I I2 connects the pair of arms I66. A yoke H3 is also pivoted to the governor shaft I66 and has a cross-bar 4 "through which a screw 6 is threaded and contacts the cross-bar II2 for adjusting the space between the respective arms for increasing or decreasing the tension on the springs H6. The yoke 3 has an extending arm 6 arranged to be engaged by a cam II1 mounted on a shaft II6, which has a bearing in the plate 21. Ra'- tation of this cam will increase or decrease the tension on the springs II6 for manually setting the governor mechanism to a different efiective position relative to the R. P. M. of the propeller. The means for operating the cam will be hereinafter more fully described, but the cam at all times acts as a stop for the tension adjusting means.

Assuming the predetermined R. P. M. of the propeller is 2006 at full throttle in sustained horiopen, thus forming an unobstructed passage bezontal flight, and the rotative speed of the crankshaft is reduced due to an increase of load, as when going into a climb, the governor arm will be drawn inwardly by the springs IIO due to the reduced centrifugal force on the weightI 01. This inward movement of the governor will cause the arm I95 to open the valve 63 permitting the fluid in the cylinder 43 to pass through the tube 69 to the cross-passage 59, through the valve 63 to the opening 64 and into the reservoir. It is to be understood that the reservoir is filled with suitable oil at the time of assembly, or can be filled through the opening I29 which is normally closed by the cap screw I2I. In order to fill the reservoir, the screw is removed and the fluid is injected under pressure preferably with an Alemite gun into the governor housing, thence into the main reservoir and into the opposite governor housing. When all the compartments and leads are completely filled the excess or overflow will be forced out the breather tube I6. The nut of the blades until such time as the load is reduced to permit the propeller to rotate at its predetermined R. P. M. As soon as this occurs the governor weight will again move outwardly to a position whereby both valves 58 and 63 are closed. Thus maintaining the propeller in this changed pitch position until the load on the drive shaft is changed by a change of maneuver;

However, if the rotative speed of the propeller is increased, as in a dive or leveling off after a climb, the load on the drive shaft will be decreased and the weight on the governor will move outwardly due to the increased centrifugal force exerted thereon, causing the valve 58 to open permitting the fluid under pressure to pass from the pumps through the passageway 54 to 51, through the valve 58 into the passageway 59, through the tube 60 into the cylinder 49 causing the cylinder to move outwardly carrying the nose therewith. As the nose moves forward the links 9| also move forward turning the propeller blades on the hub for increasing the pitch angle of the blades until the load reduces the rotative speed of the propeller to the basic R. P. M. at which time the weight will again assume its balanced position with both valves closed.

In the opposite cavity 41, the full feathering governor mechanism is mounted. This governor mechanism is set to operate at a low R. P. M. for example 500 R. P. M. and comprises a shaft I39 suitably journalled in the housing and plate. A governor arm I3I is fixed to the shaft and has a weight or ball I32 on its extending end. A spring I33 is attached to the governor arm and to a fixed part of the housing for drawing the governor inwardly beyond its neutral position, when the rotative speed of the propeller is reduced below the set R. P. M., in this case 500 R. P. M. A pair of arms I34 and I35 fixed to the shaft engage valve stems I36 and I31 of the full feathering valves 66 and I2.

During flight and when the propeller is turning over at a rate above 500 R. P. M. the governor arm is maintained in an outward position due to the centrifugal force and the valve I2 is tween the full feathering cylinder and thereservoir. 'The full feathering piston moves with the controllable pitch cylinder in its cycle of operation, and this vent to the reservoir permits free movement of the full feathering piston. When the propeller slows down below 500 R. P. M. the governor will open the valve 66 and close the valve I2, thus fluid under pressure will be forced from the pumps through the passages 53 and 54, through passage 65 past the valve 66 through passages 61, 69 and 69 into the cylinder 59, moving the piston 5| outwardly. At-this time the parts are in the position shown in Figure 2. As fluid under pressure is pumped into cylinder 59, piston 5I is moved to the left as viewed in this figure, moving the nose in a corresponding direction. Cylinder 49 will remain stationary until collar 84 engages projection 8|, when this cylinder will be pulled to the left along with the nose. When the central part of the cylinder 49 guided on the cylinder 59 contacts the collar 85, further travel of the nose in this direction will be limited.

As the nose 82 moved forward the links 9| rotated the propeller blades to a full feathering position, being an edgewise position relative to the airstream, thus reducing the head resistance of a dead propeller as well as eliminating the windmill efifect, when the motor is dead. The arrangement described allows the nose to move much further under the action of the piston 5I' than under the influence of cylinder 49, a lost motion arrangement being provided in that the cylinder 49 travels with the piston 5| through only the latter portion of the travel of said piston.

When the propeller is in a. state of rotation a centrifugal force will occur in the rotating blades, and as a result every particle of mass within the blades will try to position themselves as far away from the center of rotation as possible. As a result of this a strong turning force is created which tends to rotate the blades about their longitudinal axes toward the low pitch position. As the propeller rotates above 500 R. P. M. the valve 66 will close and the valve II will open, providing a free passage from the cylinder to the reservoir through the passages 69, 69, 61, 'II and as valve I2 is open, through port I3 into the reservoir. The rotative force exerted on the blades will cause the blades to seek their lowest pitch position, as they are free to rotate about their hubs, and the fluid in the cylinder 59 will be forced back into the reservoir. Also the fluid in the cylinder 49 will be forced into the reservoir as the valve 63 is open until the propeller has reached sufflcient speed to cause the governor I96 to move outwardly to close the valve.

I have also provided means for manually controlling the controllable pitch governor mechanism through rotation of the cam I H for increasing or decreasing the tension on the springs H0. The means employed comprises a speed reducing unit I59 (see Figs. 3, 7 and 8). A star wheel I5I is fixed to a shaft I52 supported in suitable bearings and rotating with the propeller mounting about the axis of the drive shaft. Located within the reach of the pilot is a Bowden wire" control similar to an ordinary choke button, and this wire connects to an arm I53 pivoted to the motor housing. An actuating pin I54 is mounted in a support on the motor housing, and upon pushing in on the arm I53 places the pin in the path of the star wheel, whereby upon each revolution of the propeller a partial revolution of the shaft I52 takes place. The speed reducing unit I80 comprises a gear I fixed to the shaft I52 and meshes with a gear I" on a stud shaft I51.

The gear I 88 has a gear I 58 fixed thereto which meshes with an idler gear I58, having a gear I88 fixed thereto, for transmitting motion to idler gear I6I having gear I82 attached thereto for imparting rotation to gear I83 fixed to the cam shaft I I8 for slowly rotating the cam II1.

Therefore, once the tachometer reading is known for a given pitch angle of the propeller- (which is established by the basic adjustment of the screw H) at a given throttle position, then it is only necessary for the pilot to observe the decrease in tachometer reading when increasing suflicient length of time to allow the blades to attain their full feathered position, I provide manual means for operating the full feathering mechanism from the pilot's cockpit.

The present day production motor is provided with a drive shaft which is hollow as indicated at I18, with a collector ring "I having a passage I12 communicating with the collector ring. Advantage is taken of this construction for the single purpose of operating the manual ful feathering feature of the invention.

A simple embodiment of the manual means is shown in the diagrammatic view of Fig. 11, wherein the fluid supply is held in a tank I13 and pumped therefrom by means of a hand pump I14, through a tubular connection I15. A tubular member I16 connects the pump with a pipe I11 connecting an accumulator I18 with the collector ring I1 I. A check-valve I18 is in the pipe I18 and a hand controlled valve I80 is in the pipe I11. I provide a plug I8I in the hollow drive shaft, and the plate 21 is provided with an extending boss to which a tube I82 is secured having its extending end provided with means for sealing the tube to the hollow shaft. The end of the tube is provided with a check-valve I83, and having connection with the passage '69. Thus when it is desired to use the manual full feathering mechanism, the hand pump is operated to build up a supply of fluid in the accumulator, the valve I80 is opened to permit the fluid to enter the collector ring and pass to the hollow shaft through the tube I82, past the check-valve I83 into the passage 68 for creating a pressure on the full feathering piston 5| and moving it endwise to full feather the propeller blades. when the motor is again started and the propeller attains a speed above 500 R. P. M. the valves 58 and 86 will close and the valves 12 and 63 will be open. The fluid being forced out of the cylinder, as previously described under the automatic full feathering, will pass through the passage 69 being prevented from re-entering the tube I82 by the check-valve I83. will pass through the passages 88 and 61 past the valve 12 and through the port 13 into the reservoir. If the reservoir was completely full previous to the operation of the manual full feathering operation, the excess fluid will be forced out of the vent tube 18.

It will be apparent from th foregoing, that I have devised a practical and complete mechanism for controlling the pitch of the propeller to maintain a constant propeller speed under all conditions as well as providing means for full feather ing the propeller when the motor is dead .or its speed reduced below a set R. P. M. Means have also been provided to manually change the basic R. P. M. setting of the governor.

It is apparent that the constant speed or R. P. M. is, of course, predetermined for any particular propeller and engine combination, and the basic setting of this speed is preset at the time of installation; however, in addition to this the manual control is installed in the pilot's cockpit in order to alter this basic setting within certain limits while in flight in order to obtain the maximum fuel economy when on an extended flight The fact that the fluid system employed to operate the pitch changes is completely isolated from the motor is of particular importance due to the fact that an anti-freeze solution may be used without the danger of contaminating the motor lubricating oil.

Having thus fully described my invention, what I claim as new and desire to secure by Letters Patent is: v

1. A propeller for aircraft adapted to have its blades held in normal low-pitch position by ,centrifugal force acting on the mass of the blades, an isolated fluid system, means imparted by the rotation of said propeller for creating a pressure in said fluid system, means for changing the pitch of said propeller blades operated by said fluid system andcgoverned by the speed of said propeller, and means for full feathering said propeller blades automatically upon reduction of the rate of rotation of said propeller below a predetermined speed.

2. A propeller for aircraft adapted to have its blades held in normal low-pitch position by centrifugal force acting on the mass of the blades, an isolated fluid system, means imparted by the rotation of said propeller for creating a pressure in said fluid system, means for increasing the pitch of said propeller blades operated by said fluid system and governed by the speed of said propeller, means for full feathering said propeller blades automatically upon reduction of .the

rate of rotation of said propeller below a predetermined speed and means for manually full feathering said propeller blades;

3. A propeller for aircraft adapted to have its blades held in normal low-pitch position by contrifugal force acting on the mass of the blades, an isolated fluid system, means for creating a pressure in said fluid system, means for increasing the pitch of said propeller blades operated by the pressure in said fluid system and governed by the speed of said propeller, means for manually changing the effective speed for changing the pitch of said propeller blades, and means operable through said fluid system for full feathering said propeller blades automatically upon reduction of rotative speed of said propeller below a predetermined speed.

4. A propeller structure for an aircraft comprising a drive-shaft, a hub structure fixed to said drive-shaft provided with extending stud-shafts,

Y propeller blades rotatable on said stud-shafts, a

.fluid to said cylinder, a nose mounted on said cylinder, links connecting said nose to said propeller blades, whereby upon movement being imparted to said cylinder said blades will be rotated on their respective stud-shafts for changing their pitch angle.

5. A propeller structure for an aircraft comprising a drive-shaft, a hub structure fixed to said drive-shaft provided with extending studshafts, propeller blades rotatably mounted on said stud-shafts, a housing secured to the forward end of said drive-shaft and hub, an independent fluid system wholly within said housing, means for creating a pressure in part of said system, govemor mechanisms mounted within said housing actuated by the rotative speed of said propeller, a nose mounted on said housing, a pair of cylinders connecting said nose to said housing, valves in said fluid system operable by said governor mechanisms for emitting fluid under pressure to said cylinders, one of said cylinders operable for increasing the pitch of said propeller blades and the other cylinder operable for full feathering said propeller blades, and links connecting said nose to said propeller blades whereby movement of said nose will cause rotative movement of said propeller blades for changing their pitch angles.

6. A controllable pitch propeller comprising a drive-shaft, a hub on said drive-shaft provided with extending stud-shafts, propeller blades rotatably mounted on said stud-shafts, a housing secured to the forward end of said drive-shaft,

an independent fluid system within said housing,

means for creating a pressure in part of said system, a governor mechanism mounted in said housing actuated by the rotative speed of said propeller, a nose endwise movable on said housing, an expansion chamber motor within the nose included in the fluid system for effecting movement of the nose in a forward direction, links connecting said nose to the respective propeller blades, said governor mechanism controlling the actuation of said motor to move said nose forward and increase the pitch of said propeller blades, said blades being'so arranged that centrifugal force tends to move the nose rearwardly and decrease the pitch of the blades.

7. A propeller for an aircraft having a predesystem, means in said system to maintain said predetermined propeller speed by varying the pitch of said propeller blades, and further means operable through said fluid system for automatically full feathering said propeller blades upon reduction of rotative speed of said propeller below a predetermined speed.

8. A propeller unit for an aircraft having a predetermined rotative speed, an independent fluid system wholly within said unit, speed-responsive means in said system to maintain said predetermined propeller speed by varying the pitch of said propeller blades, and means for manually full feathering said propeller.

9. A propeller for an aircraft having a predetermined rotative speed, an independent fluid system, means in said system to maintain said predetermined propeller speed by varying the pitch of said propeller blades, further means operable through said fluid system for automatically full feathering said propeller blades upon reduction of rotative speed of said propeller below a predetermined speed, and means for manually full feathering said propeller.

10. A propeller for an aircraft having a predetermined rotative speed, an independent fluid system, means in said system to maintain said predetermined propeller speed by varying the .termined rotative speed, an independent fluid l" pitch of said propeller blades, means for manually changing the predetermined rotative speed in flight, and further means operable through said fluid system for automatically full feathering said propeller upon reduction of rotative speed of said propeller below a predetermined speed.

11. A propeller for an aircraft having a predetermined rotative speed, an independent fluid system, means in said system to maintain said predetermined propeller speed by varying the pitch of said propeller blades, means for manually changing the predetermined rotative speed in flight, further means operable through said fluid system, for automatically full feathering said propellefupon reduction of rotative speedof said propeller below a predetermined speed, and means for manually full feathering said propeller blades.

12. A variable pitch propeller having blades adjustable from a low pitch position to a high pitch position and also adjustable to a full feathered position, a motor for adjusting the blades in the range between the low and high pitch positions, and a second motor for adjusting the blades to the full feathered position, and a control system including speed responsive means through which operation of said motors is controlled in such manner as to normally exclude operation of the latter motor while the former is functioning.

13. A variable pitch propeller having blades adjustable from a low pitch position to 'a high pitch position and also adjustable to a full feathered position, an actuating mechanism for adjusting the blades in the range between the low and high pitch positions, a second actuating mechanism for adjusting the blades to the full feathered position, and speed-responsive devices for controlling both of said actuating mechamsms.

14. A variable pitch propeller having blades adjustable from a low pitch position to a high pitch position and also adjustable to a full feathered position, an actuating mechanism for adjusting the blades in the range between the low and high pitch positions, a second actuating mechanism for adjusting the blades to the full feathered position, speed-responsive devices for controlling both of said actuating mechanisms, and manually operable means in addition to the speed-responsive means for effecting operation of both of said mechanisms.

15. A variable pitch propeller having blades adjustable about their axes from a position of low pitch to a position of high pitch and further movable from one of such positions to full feathered position, two motor devices for adjusting the blades of the propeller and being operatively connected therewith, one of said devices turning the blades in the range between the said low and highpitch positions, the other of said devices turning the blades to the full feathered position, and speed-responsive means correlating the operation of the two motor devices.

16. A variable pitch-propeller having blades adjustable about their axes from a position of low pitch to a position of high pitch and further movable from one of such positions to full feathered position, two motor devices for adjusting the blades of the propeller and being operatively connected therewith, one of said devices turning the blades in the range between the said low and and speed-responsive means correlating the operation' of the two motor devices including a common fluid pressure system and separate speed-responsive governor-operated valves in the system, one for each motor.

17. A variable pitch propeller comprising a hub having blades thereon adjustable about their Y means within the hub for moving said element through a range to rotate the blades between the low and high pitch positions, and a second fluid pressure actuated device in the hub for operating said element to turn the blades to the full feathered position.

motors, and means operatively connecting the adjustable blades with the nose.

22. A variable pitch propeller comprising a hub having adjustable blades thereon, said-blades being adjustable from low pitch position to a high pitch position and being further adjustable to a full feathered position, said blades being of a character such that centrifugal force serves to normally move the blades to the low pitch position when the propeller is revolving, a fluid pressure motor for moving the blades from the low pitch position over a range of positions to the 18'. A variable pitch propeller having blades adjustable about their axes, an operating element for actuating the blades, a system of two expansible chamber; motors for independently moving said operating element, one through the full range of its movement and the other through a limited range only, there being a lost motion connection between the latter and the operating element, and a fluid pressure system for opeiating said expansible chamber motors.

19. A variable pitch propeller having blades adjustable about their axes, an operating element for actuating the blades, a system of two expansible chamber motors for independently moving said operating element, one through the full range of its movement and the other through a limited range only, there being a lost motion connection between the latter and the operating element, a common fluid pressure system for op:

erating both of said expansible chamber motors, and means for controlling their operation according to the speed of the propeller.

20. A variable pitch propeller having blades adjustable about their axes, an operating element for actuating the blades, a system of two expansible chamber motors for independently moving said operating element, one through the full range of its movement and the other through a limited range only, there being a lost motion connection between the latter and the operating element, a common fluid. pressure system for operating both of said expansible chamber motors, means for controlling their operation according to the speed of the propeller, and manually operable devices for effecting operation of said motors and rendering the speed-responsive means ineffective.

.21. A variable pitch propeller comprising a hub having adjustable blades thereon movable between low pitch and high pitch positions and also movable to a full feathered position, means inthe rotation thereof for delivering fluid from the reservoir to the expansible chamber motors, speed-responsive valves for controlling the delivery of fluid from the pump to said respective high pitch position, a second fluid pressure motor for moving the blades to a full feathered position, means for supplying fluid pressure to said motors, and governor-controlled valves for controlling the escape of fluid from said motors. said fluid pressure motors beingarranged too'perate in opposition to the centrifugal action which turns the blades to low pitchposition.

23. A variable pitch propeller comprising a hub having blades thereon which are axially adjustable and movable from a low pitch position to a high pitch position and also movable to a full feathered position, means carried by the hub for controlling the adjustment of the blades in the range between the low pitch and high pitch positions, means dependent upon the speed of rotation of the propeller for automatically controlling said first means, manually operable means having blades thereon which are axially adjust able andmovable'from a low pitch position to a high pitch position and also movable to a full feathered position, means carried by the hub for controlling the adjustment of the blades in the range between the low pitch and high pitch positions, means dependent upon the speed of rotation of the propeller for automatically controlling said first means, manually operable means for effecting adjustment of the propeller independent of said speed-responsive means, and manually operable means for effecting such full feathering operation.

25. A variable pitch propeller unit comprising a shaft, a hub fixed on the shaft, adjustable blades on the hub, a blade-actuating unit secured to the hub and shaft assembly at the forward end of the shaft, said unit comprising members constituting a concentric reservoir and expansible chamber fluid pressure motor, pump means in said unit operated directly and entirely through the rotation of the propellerfor circulating fluid through the motor and reservoir, valve means in said unit for controlling such circulation, and speed-responsive means for controlling the valve.

26. A variable pitch propeller unit comprising a shaft, a hub fixed on the shaft, adjustable blades on the hub, a blade-actuatingunit secured to the hub and shaft assembly at the forward end of the shaft, said unit comprising members" constituting a concentric reservoir and expansible chamber fluid pressure motor, pump means in said unit driven entirely through the rotation of the propeller for circulating fluid through the motor and reservoir, valve means in said unit for controlling such circulation, speed-responsive means for controlling the valve, and manually adjustable means for independently actuating the valve.

27. An attachment for operating the blades of an adjustable pitch propeller, comprising a member adapted to be secured to the forward end of a propeller shaft in advance of the hub of the propeller, said member supporting a reservoir, an expansible chamber fluid pressure motor, said member also carrying a pump driven entirely by the rotation of the adjustable pitch propeller and valves for circulating fluid through th reservoir and motor, and means for transmitting motion from the motor to the adjustable blades of the-propeller to which the unit is attached.

28. The combination with a variable pitch propeller having angularly adjustable blades mov able from a position of low pitch angle through a position of high pitch angle to a full feathered position, a motor system comprising motor means and speed-responsive means driven by the propeller for operating the blades from a high pitch angle to a low pitch angle on slowing down of the propeller within a given range and automatically operable upon slowing of the propeller below such range to move the blades from the low pitch angle through a position of high pitch angle to the full feathered position.

29. A variable pitch propeller having blades adjustable from a low pitch position to a high pitch position and also adjustable to a full feathered position, fluid actuating means responsive to the speed of the propeller for adjusting the blades in the range between the low pitch and the high pitch positions, manually operable means for controlling said actuating means to selectively adjust the blades in the range between the'low and the high pitch positions, a second actuating means for full feathering the propeller, a common movable member to which each of said actuating means directly transmits its motion, said member being spaced from the blades, and operating connections between said common movable member and the propeller blades.

30. A variable pitch propeller having blades adjustable from a low pitch position to a high pitch position and also adjustable to a full feathered position, actuating means responsive to the speed of the propeller for adjusting the blades in the range between the low pitch and the high pitch positions, manually operable means for controlling the said actuating means to selectively determine the position of the blades in the range between the low and the high pitch position, a second actuating means automatically responsive to a predetermined abnormally low speed of the propeller for moving the blades to a full feathered position, and common connections for transmitting motion from both of said actuating means to the propeller blades.

31. A propeller for airplanes comprising a hub, blades on the hub movable on the hub through a varying range of pitch angles, a propeller mounting with respect to which the hub rotates, a pump within the hub, cooperating means on the hub and mounting for positively driving the pump upon rotation of the propeller, a fluid reservoir within the hub, a fluid pressure motor means within the hub to which the pump supplies fluid, a distributing valve in the hub for controlling the flow of fluid from the pump through the motor, speed-responsive means within the hub for operating the distributing valve and means for transmitting motion from the motor means to the propeller blades to vary the pitch angle thereof.

32. The combination with a variable pitch propeller having angularly adjustable blades, of servo-motor means for moving the blades in a constantly increasing pitch angle to-a full feathered postion, and speed-responsive means independent of the blades automatically operable upon the slowing down of the propeller to a predetermined abnormally low speed for controlling the operation of said first means.

ARTHUR G. RINDFLEISCH. 

